The Ossau valley is one of the three large mountain valleys of Béarn. It stretches geographically from north to south over fifty kilometers from Rébénacq (fifteen kilometers from Pau) to the Col du Pourtalet (on the Spanish border).
It is crossed by the Gave d'Ossau and dominated by the Pic du Midi d'Ossau which rises to 2,884 meters. Located in Haut-Béarn south of Pau, it is crossed by the Gave d'Ossau, mother branch of the Gave d'Oloron. It communicates with the Ouzom valley and Lavedan (Argelès-Gazost), to the east, by the Aubisque pass and with Aragon, to the south, by the Pourtalet pass.